/*
 * Copyright (C) Lucent Technologies 1997
 * All Rights Reserved
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby
 * granted, provided that the above copyright notice appear in all
 * copies and that both that the copyright notice and this
 * permission notice and warranty disclaimer appear in supporting
 * documentation, and that the name Lucent Technologies or any of
 * its entities not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.
 *
 * LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
 * IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
 * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
 * THIS SOFTWARE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "awk.h"
#include "y.tab.h"

extern YYSTYPE	yylval;
extern int	infunc;

off_t	lineno	= 1;
int	bracecnt = 0;
int	brackcnt  = 0;
int	parencnt = 0;

typedef struct Keyword {
	const char *word;
	int	sub;
	int	type;
} Keyword;

Keyword keywords[] = {	/* keep sorted: binary searched */
	{ "BEGIN",	XBEGIN,		XBEGIN },
	{ "END",	XEND,		XEND },
	{ "NF",		VARNF,		VARNF },
	{ "atan2",	FATAN,		BLTIN },
	{ "break",	BREAK,		BREAK },
	{ "close",	CLOSE,		CLOSE },
	{ "continue",	CONTINUE,	CONTINUE },
	{ "cos",	FCOS,		BLTIN },
	{ "delete",	DELETE,		DELETE },
	{ "do",		DO,		DO },
	{ "else",	ELSE,		ELSE },
	{ "exit",	EXIT,		EXIT },
	{ "exp",	FEXP,		BLTIN },
	{ "fflush",	FFLUSH,		BLTIN },
	{ "for",	FOR,		FOR },
	{ "func",	FUNC,		FUNC },
	{ "function",	FUNC,		FUNC },
	{ "getline",	GETLINE,	GETLINE },
	{ "gsub",	GSUB,		GSUB },
	{ "if",		IF,		IF },
	{ "in",		IN,		IN },
	{ "index",	INDEX,		INDEX },
	{ "int",	FINT,		BLTIN },
	{ "length",	FLENGTH,	BLTIN },
	{ "log",	FLOG,		BLTIN },
	{ "match",	MATCHFCN,	MATCHFCN },
	{ "next",	NEXT,		NEXT },
	{ "nextfile",	NEXTFILE,	NEXTFILE },
	{ "print",	PRINT,		PRINT },
	{ "printf",	PRINTF,		PRINTF },
	{ "rand",	FRAND,		BLTIN },
	{ "return",	RETURN,		RETURN },
	{ "sin",	FSIN,		BLTIN },
	{ "split",	SPLIT,		SPLIT },
	{ "sprintf",	SPRINTF,	SPRINTF },
	{ "sqrt",	FSQRT,		BLTIN },
	{ "srand",	FSRAND,		BLTIN },
	{ "sub",	SUB,		SUB },
	{ "substr",	SUBSTR,		SUBSTR },
	{ "system",	FSYSTEM,	BLTIN },
	{ "tolower",	FTOLOWER,	BLTIN },
	{ "toupper",	FTOUPPER,	BLTIN },
	{ "while",	WHILE,		WHILE },
};

#define	RET(x)	{ if (dbg) (void) printf("lex %s\n", tokname(x)); return (x); }

int
peek(void)
{
	int c = input();
	unput(c);
	return (c);
}

int
gettok(char **pbuf, size_t *psz)	/* get next input token */
{
	int c, retc;
	char *buf = *pbuf;
	size_t sz = *psz;
	char *bp = buf;

	c = input();
	if (c == 0)
		return (0);
	buf[0] = c;
	buf[1] = 0;
	if (!isalnum(c) && c != '.' && c != '_')
		return (c);

	*bp++ = c;
	if (isalpha(c) || c == '_') {	/* it's a varname */
		for (; (c = input()) != 0; ) {
			if (bp-buf >= sz &&
			    !adjbuf(&buf, &sz, bp-buf+2, 100, &bp, "gettok"))
				FATAL("out of space for name %.10s...", buf);
			if (isalnum(c) || c == '_')
				*bp++ = c;
			else {
				*bp = 0;
				unput(c);
				break;
			}
		}
		*bp = 0;
		retc = 'a';	/* alphanumeric */
	} else {	/* maybe it's a number, but could be . */
		char *rem;
		/* read input until can't be a number */
		for (; (c = input()) != 0; ) {
			if (bp-buf >= sz &&
			    !adjbuf(&buf, &sz, bp-buf+2, 100, &bp, "gettok"))
				FATAL("out of space for number %.10s...", buf);
			if (isdigit(c) || c == 'e' || c == 'E' ||
			    c == '.' || c == '+' || c == '-')
				*bp++ = c;
			else {
				unput(c);
				break;
			}
		}
		*bp = 0;
		(void) strtod(buf, &rem);	/* parse the number */
		if (rem == buf) {	/* it wasn't a valid number at all */
			buf[1] = 0;	/* return one character as token */
			retc = buf[0];	/* character is its own type */
			unputstr(rem+1); /* put rest back for later */
		} else {	/* some prefix was a number */
			unputstr(rem);	/* put rest back for later */
			rem[0] = 0;	/* truncate buf after number part */
			retc = '0';	/* type is number */
		}
	}
	*pbuf = buf;
	*psz = sz;
	return (retc);
}

int	word(char *);
int	string(void);
int	regexpr(void);
int	sc	= 0;	/* 1 => return a } right now */
int	reg	= 0;	/* 1 => return a REGEXPR now */

int
yylex(void)
{
	int c;
	static char *buf = NULL;
	/* BUG: setting this small causes core dump! */
	static size_t bufsize = 5;

	if (buf == NULL && (buf = (char *)malloc(bufsize)) == NULL)
		FATAL("out of space in yylex");
	if (sc) {
		sc = 0;
		RET('}');
	}
	if (reg) {
		reg = 0;
		return (regexpr());
	}
	for (;;) {
		c = gettok(&buf, &bufsize);
		if (c == 0)
			return (0);
		if (isalpha(c) || c == '_')
			return (word(buf));
		if (isdigit(c)) {
			yylval.cp = setsymtab(
			    buf, tostring(buf), atof(buf), CON|NUM, symtab);
			/* should this also have STR set? */
			RET(NUMBER);
		}

		yylval.i = c;
		switch (c) {
		case '\n':	/* {EOL} */
			lineno++;
			RET(NL);
		case '\r':	/* assume \n is coming */
		case ' ':	/* {WS}+ */
		case '\t':
			break;
		case '#':	/* #.* strip comments */
			while ((c = input()) != '\n' && c != 0)
				;
			unput(c);
			break;
		case ';':
			RET(';');
		case '\\':
			if (peek() == '\n') {
				(void) input();
				lineno++;
			} else if (peek() == '\r') {
				(void) input();
				(void) input();	/* BUG: check for \n */
				lineno++;
			} else {
				RET(c);
			}
			break;
		case '&':
			if (peek() == '&') {
				(void) input();
				RET(AND);
			} else
				RET('&');
		case '|':
			if (peek() == '|') {
				(void) input();
				RET(BOR);
			} else
				RET('|');
		case '!':
			if (peek() == '=') {
				(void) input();
				yylval.i = NE;
				RET(NE);
			} else if (peek() == '~') {
				(void) input();
				yylval.i = NOTMATCH;
				RET(MATCHOP);
			} else
				RET(NOT);
		case '~':
			yylval.i = MATCH;
			RET(MATCHOP);
		case '<':
			if (peek() == '=') {
				(void) input();
				yylval.i = LE;
				RET(LE);
			} else {
				yylval.i = LT;
				RET(LT);
			}
		case '=':
			if (peek() == '=') {
				(void) input();
				yylval.i = EQ;
				RET(EQ);
			} else {
				yylval.i = ASSIGN;
				RET(ASGNOP);
			}
		case '>':
			if (peek() == '=') {
				(void) input();
				yylval.i = GE;
				RET(GE);
			} else if (peek() == '>') {
				(void) input();
				yylval.i = APPEND;
				RET(APPEND);
			} else {
				yylval.i = GT;
				RET(GT);
			}
		case '+':
			if (peek() == '+') {
				(void) input();
				yylval.i = INCR;
				RET(INCR);
			} else if (peek() == '=') {
				(void) input();
				yylval.i = ADDEQ;
				RET(ASGNOP);
			} else
				RET('+');
		case '-':
			if (peek() == '-') {
				(void) input();
				yylval.i = DECR;
				RET(DECR);
			} else if (peek() == '=') {
				(void) input();
				yylval.i = SUBEQ;
				RET(ASGNOP);
			} else
				RET('-');
		case '*':
			if (peek() == '=') {	/* *= */
				(void) input();
				yylval.i = MULTEQ;
				RET(ASGNOP);
			} else if (peek() == '*') {	/* ** or **= */
				(void) input();	/* eat 2nd * */
				if (peek() == '=') {
					(void) input();
					yylval.i = POWEQ;
					RET(ASGNOP);
				} else {
					RET(POWER);
				}
			} else
				RET('*');
		case '/':
			RET('/');
		case '%':
			if (peek() == '=') {
				(void) input();
				yylval.i = MODEQ;
				RET(ASGNOP);
			} else
				RET('%');
		case '^':
			if (peek() == '=') {
				(void) input();
				yylval.i = POWEQ;
				RET(ASGNOP);
			} else
				RET(POWER);

		case '$':
			/* BUG: awkward, if not wrong */
			c = gettok(&buf, &bufsize);
			if (isalpha(c)) {
				if (strcmp(buf, "NF") == 0) {
					/* very special */
					unputstr("(NF)");
					RET(INDIRECT);
				}
				c = peek();
				if (c == '(' || c == '[' ||
				    (infunc && isarg(buf) >= 0)) {
					unputstr(buf);
					RET(INDIRECT);
				}
				yylval.cp = setsymtab(
				    buf, "", 0.0, STR|NUM, symtab);
				RET(IVAR);
			} else if (c == 0) {	/*  */
				SYNTAX("unexpected end of input after $");
				RET(';');
			} else {
				unputstr(buf);
				RET(INDIRECT);
			}

		case '}':
			if (--bracecnt < 0)
				SYNTAX("extra }");
			sc = 1;
			RET(';');
		case ']':
			if (--brackcnt < 0)
				SYNTAX("extra ]");
			RET(']');
		case ')':
			if (--parencnt < 0)
				SYNTAX("extra )");
			RET(')');
		case '{':
			bracecnt++;
			RET('{');
		case '[':
			brackcnt++;
			RET('[');
		case '(':
			parencnt++;
			RET('(');

		case '"':
			/* BUG: should be like tran.c ? */
			return (string());

		default:
			RET(c);
		}
	}
}

int
string(void)
{
	int c, n;
	char *s, *bp;
	static char *buf = NULL;
	static size_t bufsz = 500;

	if (buf == NULL && (buf = (char *)malloc(bufsz)) == NULL)
		FATAL("out of space for strings");
	for (bp = buf; (c = input()) != '"'; ) {
		if (!adjbuf(&buf, &bufsz, bp-buf+2, 500, &bp, "string"))
			FATAL("out of space for string %.10s...", buf);
		switch (c) {
		case '\n':
		case '\r':
		case 0:
			*bp = '\0';
			SYNTAX("non-terminated string %.10s...", buf);
			if (c == 0)	/* hopeless */
				FATAL("giving up");
			lineno++;
			break;
		case '\\':
			c = input();
			switch (c) {
			case '"': *bp++ = '"'; break;
			case 'n': *bp++ = '\n'; break;
			case 't': *bp++ = '\t'; break;
			case 'f': *bp++ = '\f'; break;
			case 'r': *bp++ = '\r'; break;
			case 'b': *bp++ = '\b'; break;
			case 'v': *bp++ = '\v'; break;
			case 'a': *bp++ = '\007'; break;
			case '\\': *bp++ = '\\'; break;

			case '0': case '1': case '2': /* octal: \d \dd \ddd */
			case '3': case '4': case '5': case '6': case '7':
				n = c - '0';
				if ((c = peek()) >= '0' && c < '8') {
					n = 8 * n + input() - '0';
					if ((c = peek()) >= '0' && c < '8')
						n = 8 * n + input() - '0';
				}
				*bp++ = n;
				break;

			case 'x': {	/* hex  \x0-9a-fA-F + */
				char xbuf[100], *px;
				px = xbuf;
				while ((c = input()) != 0 && px-xbuf < 100-2) {
					if (isdigit(c) ||
					    (c >= 'a' && c <= 'f') ||
					    (c >= 'A' && c <= 'F'))
						*px++ = c;
					else
						break;
				}
				*px = 0;
				unput(c);
				(void) sscanf(xbuf, "%x", (unsigned int *)&n);
				*bp++ = n;
				break;
			}

			default:
				*bp++ = c;
				break;
			}
			break;
		default:
			*bp++ = c;
			break;
		}
	}
	*bp = 0;
	s = tostring(buf);
	*bp++ = ' '; *bp++ = 0;
	yylval.cp = setsymtab(buf, s, 0.0, CON|STR|DONTFREE, symtab);
	RET(STRING);
}


int
binsearch(char *w, Keyword *kp, int n)
{
	int cond, low, mid, high;

	low = 0;
	high = n - 1;
	while (low <= high) {
		mid = (low + high) / 2;
		if ((cond = strcmp(w, kp[mid].word)) < 0)
			high = mid - 1;
		else if (cond > 0)
			low = mid + 1;
		else
			return (mid);
	}
	return (-1);
}

int
word(char *w)
{
	Keyword *kp;
	int c, n;

	n = binsearch(w, keywords, sizeof (keywords) / sizeof (keywords[0]));
	if (n != -1) {	/* found in table */
		kp = keywords + n;
		yylval.i = kp->sub;
		switch (kp->type) {	/* special handling */
		case BLTIN:
			if (kp->sub == FSYSTEM && safe)
				SYNTAX("system is unsafe");
			RET(kp->type);
		case FUNC:
			if (infunc)
				SYNTAX("illegal nested function");
			RET(kp->type);
		case RETURN:
			if (!infunc)
				SYNTAX("return not in function");
			RET(kp->type);
		case VARNF:
			yylval.cp = setsymtab("NF", "", 0.0, NUM, symtab);
			RET(VARNF);
		default:
			RET(kp->type);
		}
	}
	c = peek();	/* look for '(' */
	if (c != '(' && infunc && (n = isarg(w)) >= 0) {
		yylval.i = n;
		RET(ARG);
	} else {
		yylval.cp = setsymtab(w, "", 0.0, STR|NUM|DONTFREE, symtab);
		if (c == '(') {
			RET(CALL);
		} else {
			RET(VAR);
		}
	}
}

void
startreg(void)	/* next call to yylex will return a regular expression */
{
	reg = 1;
}

int
regexpr(void)
{
	int c;
	static char *buf = NULL;
	static size_t bufsz = 500;
	char *bp;

	if (buf == NULL && (buf = (char *)malloc(bufsz)) == NULL)
		FATAL("out of space for rex expr");
	bp = buf;
	for (; (c = input()) != '/' && c != 0; ) {
		if (!adjbuf(&buf, &bufsz, bp-buf+3, 500, &bp, "regexpr"))
			FATAL("out of space for reg expr %.10s...", buf);
		if (c == '\n') {
			*bp = '\0';
			SYNTAX("newline in regular expression %.10s...", buf);
			unput('\n');
			break;
		} else if (c == '\\') {
			*bp++ = '\\';
			*bp++ = input();
		} else {
			*bp++ = c;
		}
	}
	*bp = 0;
	if (c == 0)
		SYNTAX("non-terminated regular expression %.10s...", buf);
	yylval.s = tostring(buf);
	unput('/');
	RET(REGEXPR);
}

/* low-level lexical stuff, sort of inherited from lex */

char	ebuf[300];
char	*ep = ebuf;
char	yysbuf[100];	/* pushback buffer */
char	*yysptr = yysbuf;
FILE	*yyin = NULL;

int
input(void)	/* get next lexical input character */
{
	int c;
	extern char *lexprog;

	if (yysptr > yysbuf)
		c = (uschar)*--yysptr;
	else if (lexprog != NULL) {	/* awk '...' */
		if ((c = (uschar)*lexprog) != 0)
			lexprog++;
	} else				/* awk -f ... */
		c = pgetc();
	if (c == EOF)
		c = 0;
	if (ep >= ebuf + sizeof (ebuf))
		ep = ebuf;
	*ep = c;
	if (c != 0) {
		ep++;
	}
	return (c);
}

void
unput(int c)	/* put lexical character back on input */
{
	if (yysptr >= yysbuf + sizeof (yysbuf))
		FATAL("pushed back too much: %.20s...", yysbuf);
	*yysptr++ = c;
	if (--ep < ebuf)
		ep = ebuf + sizeof (ebuf) - 1;
}

void
unputstr(const char *s)	/* put a string back on input */
{
	int i;

	for (i = strlen(s)-1; i >= 0; i--)
		unput(s[i]);
}
